Visa is investigating a potential security breach at an European payment processor that might have affected cardholders in eastern Europe.

Romanian banks are alerted about a payment card breach that affects eastern European cardholders

Visa is investigating a potential security breach at an European payment processor that might have affected cardholders in eastern Europe.

"Visa Europe has been informed of a potential data security breach at a European processor and an investigation is underway," the company said in a statement. "We are working closely with our member banks to ensure cardholders are protected," it added.

The potentially affected payment processor is serving an undisclosed merchant chain that does business in several eastern European markets, Visa said.

Multiple banks have been alerted and some have already taken steps to limit the potential fraud. Romanian state-owned CEC Bank is in the process of reissuing 17,000 payment cards as a result of the incident.

The bank received official reports according to which information corresponding to a number of payment cards issued by Romanian and foreign financial institutions had been compromised.

CEC Bank said that the attack didn't target its customers in particular and that the compromise wasn't the result of vulnerabilities in its systems. Other banks are expected to make similar announcements in the days to come.

The Romanian Association of Banks (ARB) confirmed that some banks were alerted about a potential security breach that might have exposed information about transactions performed with some cards.

The association said in a statement posted on its website that it did not expect cardholders to be affected. If suspicious transactions are detected, customers should contact the issuing banks for clarifications, it added.

"Concerned cardholders should keep a close eye on their accounts and report any unusual or unexpected activity to their issuing bank," said Catalin Cretu, Visa Europe's country manager for Romania.

"Cardholders who are innocent victims of fraud will get their money back, subject to the terms and conditions of their bank," he explained.